1. Technical Field
The present disclosure generally relates to the field of safety needles, and more particularly, to a shielded dental safety needle for protecting practitioners from inadvertent needle contact during the transport, use and disposal of the safety needle.
2. Description of the Related Art
Medical and dental syringes contaminated with body fluids containing infectious diseases, viruses, contaminants, etc., present serious safety hazards to practitioners because of accidental contact with needles. A particular danger exists during attachment and removal of a needle from a syringe. A number of different devices have been proposed to minimize the possibility of spreading infectious disease due to accidents related to inadvertent needle stick injuries.
Typically, to reduce such safety hazards, an extendable needle shield is provided which, after the syringe has been used, can be pushed to an extended position to cover the needle. This prevents an individual from accidentally contacting the needle. Such construction commonly features a shield which locks when pushed to an extended position so that it cannot be retracted to expose the needle, except by application of extraordinary force. A number of such constructions have been proposed to satisfy a general requirement that the needle be permanently covered after use. Some of these constructions involve complex locking mechanisms when the shield is fully extended. For example, U.S. Pat. No. 4,767,413 to Haber et al. disclose a disposable dental syringe having a spring loaded mechanism to enclose a needle after use. These types of devices are not typically adaptable to standard reusable metal dental syringes and, therefore, require costly modifications to the syringes.
Another type of dental syringe having a protective needle shield is disclosed in U.S. Pat. No. 5,522,812 to Talonn et al., the entire contents of which are incorporated herein by reference. Talonn et al. show a tubular shield having one or more elongated keys which are rotated on a collar keyway to a locked position that prevents retraction of the shield. These types of devices are not easily deployed and locked with one hand because they must be rotated to a locked position. This drawback can require two-handed operability increasing the probability of accidental contact with the needle. See also U.S. Pat. Nos. 4,723,943 to Spencer and 5,254,100 to Huband.
Practitioners often use a single syringe to administer additional medication to a medical or dental patient after a first dose has been administered. Some known needle shield devices provide a temporary lock to prevent accidental needle sticks in between uses of the syringe. Spencer discloses a shield that can be rotated to a temporary lock position. The necessary rotation of these type devices is difficult with one-handed operation and, therefore, may require two-handed operation. Further, these devices do not include structure that prevents inadvertent disengagement from the temporary lock positions. These disadvantages increase the possibility of accidental contact with the needle.
Therefore, a need exists for a needle cannula apparatus having a shield that prevents inadvertent needle stick during attachment, general use and removal of a needle cannula from the needle cannula apparatus with one-handed operation. The needle cannula apparatus can also prevent inadvertent needle stick during transport and between injections. Desirably, the needle cannula apparatus has a shield that coaxially aligns a needle therewith and provides a needle straightening feature. Most desirably, the needle cannula apparatus has a shield fabricated from a transparent material whereby the shield prevents impairment and/or fogging of the transparency of the shield.
Accordingly, the present disclosure provides a needle cannula apparatus and related methods designed to shield, such as, for example, hypodermic and dental needles and protect practitioners from accidental contact with a needle during use and related operations of the needle cannula apparatus. These uses and related operations include attachment and removal of the needle from a syringe, handling of a syringe, etc.
The needle cannula apparatus disclosed has a shield that prevents inadvertent needle stick during attachment, general use and removal of a needle cannula from the needle cannula apparatus with one-handed operation. The needle cannula apparatus may also prevent inadvertent needle stick during transport and between injections. Transport includes such activities as preparation, carrying, etc., for mounting with a syringe, packaging, delivery to a location, retrieval from storage, etc. Desirably, the needle cannula apparatus has a shield that coaxially aligns a needle therewith and provides a needle straightening feature. Most desirably, the needle cannula apparatus has a shield fabricated from transparent material whereby the design of the shield prevents impairment and/or fogging of the transparency of the shield.
In one particular embodiment, a needle cannula apparatus is provided, in accordance with the present disclosure. The needle cannula apparatus includes a needle hub that is mountable to an instrument. The needle cannula apparatus has a cantilevered portion extending therefrom. The cantilevered portion has a button member and a hub stop disposed at a distal end thereof. The needle hub defines at least one tab slot having a tab slot end.
A shield is movably disposed about the needle hub and defines a shield slot configured for relative slidable movement of the button member therein. The shield slot includes a proximal enlarged slot section configured to engage the hub stop such that proximal movement of the shield is prevented. The shield further includes at least one tab stop that is configured for movement within the at least one tab slot of the needle hub and engagement with the tab slot end such that distal movement of the shield is prevented.
The needle hub may include a needle cannula coaxially mounted therewith. The needle hub may include an engagement portion configured for releasably mounting the needle hub with the instrument. The needle hub can include a proximal portion that defines an aperture having an internally or externally threaded portion or a self-threading portion configured for releasably mounting the instrument therewith. Alternatively, the needle cannula hub includes at least one hub slot and the shield includes at least one shield rail. The at least one shield rail slidably engages the at least one hub slot facilitating axial movement of the shield relative to the needle hub. Desirably, the needle hub has three hub slots and the shield has three corresponding shield rails. Most desirably, the needle hub defines two diametrically spaced tab slots and the shield further includes two diametrically spaced tab stops.
In an alternate embodiment, the proximal enlarged slot section of the shield slot is defined at a proximal portion thereof and the shield slot further defines a transport enlarged slot section disposed between a distal portion of the shield slot and the proximal enlarged slot section. The transport enlarged slot section can be configured to releasably engage the hub stop such that axial movement of the shield is prevented. The button member may be manipulable to facilitate release of the hub stop from engagement with the transport enlarged slot section facilitating axial movement of the shield.
The shield can have a range of movement between a distal position whereby a distal end of the needle hub including a needle cannula is shielded and a proximal position whereby the distal end of the needle hub including a needle cannula is fully extended. In the distal position, the hub stop can engage the proximal enlarged slot section such that proximal movement of the shield is prevented. In another embodiment, the range of movement includes a transport position whereby the transport enlarged slot section is configured to engage the hub stop such that axial movement of the shield is prevented. The button member may be manipulable to release the hub stop from the transport enlarged slot section facilitating axial movement of the shield. The button member may be releasably lockable in the transport position.
In another alternate embodiment, the shield has an inner surface formed at a distal portion thereof. The inner surface is configured to engage a distal end of the needle hub to facilitate coaxial alignment of the distal end of the needle hub with the shield. The shield can be fabricated from a substantially transparent material, such as, for example, clear polycarbonate, acrylic, etc.
The shield may also include a button cover disposed about the proximal enlarged slot section which is configured to prevent disengagement of the hub stop and the proximal enlarged slot section. The needle hub and the shield can engage to maintain the shield in the proximal position by a friction fit formed therebetween.
The shield may have an inner surface formed at a distal portion thereof. The inner surface engages the needle hub in a configuration to substantially prevent collection of substances that impair the transparency of the shield. This configuration advantageously facilitates viewing of volumetric markings in the syringe, carpule contents and flashback. Moisture from the patent""s mouth can become trapped within a shield/hub interface creating a dangerous condition for the patient and/or the practitioner. By providing structure that blocks the path of the moisture from the patient""s mouth to the inside of the shield, the occurrence of fogging may be eliminated or greatly reduced.
A method for transport and use of a needle cannula apparatus is provided. The method including the steps of: providing the needle cannula apparatus, similar to those described above; mounting a needle cannula to the needle hub; manipulating the button member within the shield slot to position the shield in a transport position to temporarily prevent axial movement of the shield; mounting the instrument to the needle cannula apparatus; and transporting the needle cannula apparatus. The method may further include the steps of: manipulating the button member to release the shield from the transport position; and manipulating the shield to a proximal position whereby the needle cannula is fully extended from a distal opening of the shield.
The method may further include the steps of: inserting the needle cannula into a subject; removing the needle cannula from the subject; and manipulating the shield to a transport position to temporarily prevent axial movement of the shield. The method can further include the steps of: manipulating the button member to release the shield from the transport position; and manipulating the button member within the shield slot to position the shield in a distal position to fixedly prevent axial movement of the shield.